


For Or Against Us?

by booksindalibrary



Series: As If Our World Wasn't Crazy Enough (Or, Vongola Gets Caught Up in a Lot of Shit) [4]
Category: Katekyou Hitman Reborn!, Percy Jackson and the Olympians - Rick Riordan
Genre: Crossover, Gen, Prophecy, Questing, idk how to tag this again lmao
Language: English
Status: In-Progress
Published: 2017-08-29
Updated: 2018-01-10
Packaged: 2018-12-21 04:28:08
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 3,735
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11936310
Author URL: https://archiveofourown.org/users/booksindalibrary/pseuds/booksindalibrary
Summary: Tsuna's seen a lot in his life, most of which have no right in existing - is it really too much of a stretch to believe in the gods?





	1. Kawahira Issues More Obscure Orders

**Author's Note:**

  * For [Morcai](https://archiveofourown.org/users/Morcai/gifts), [Plantress](https://archiveofourown.org/users/Plantress/gifts).

**Notes for the Chapter:**

> welcome to yet another waiting trainwreck from me. expect either a rlly quick update or a rlly long wait.
> 
> unproofread mess that this is, plz enjoy
> 
> Thanks to morcai and Plantress for ideas and planning w/ this!!!!

“Hey,” Kawahira said, and Tsuna fell back with a shriek, school bag hitting the ground with a  _thunk._

“Yeah, okay, that wasn't needed,” Kawahira noted, rubbing an ear. He was still smiling, despite the obvious threat Gokudera was issuing with his eyes (not to mention his Flames were already active).

“What are you doing here?” Tsuna asked, voice still too high for his own liking.

“Juudaime, don't listen to him,” Gokudera said before Kawahira could say anything. “You know we-”

“Do you want to know more about your lineage?” Kawahira interjected, and both boys fell silent.

“Yes,” Tsuna said, this time voice low and quavering. “Is this about the first generation?”

Kawahira smiled – he smirked, more like, Gokudera thought bitterly. What did he have planned?

“Why not go to America?”

“America?” Tsuna said incredulously. “I can't even speak English-”

Gokudera shifted nervously. “Juudaime, are you really going to follow what he says?”

Tsuna looked taken aback. “W-Well, if it's about...”

Gokudera sighed. “I know English,” he said resignedly. Tsuna brightened, and agreed to go to New York.

Gokudera _knew_ this would end badly.

“Hey, Reborn,” Tsuna said brightly to the baby on his shoulder, “Can you-”

“I'm not going,” Reborn said as Kawahira interrupted with, “He's not allowed to go.”

Both traded _looks_ that surpassed any glare Gokudera could pull off. Reborn, sticking up his nose, said, “I'm returning to Italy. The Ninth has orders.”

“All right,” Tsuna said, partly relieved. But then again, how would he learn English in time?

“Don't worry, I'll be there,” Gokudera said confidently, puffing up. “Juudaime! I'll have everything sorted for you.”

* * *

“We're here...but do _we really need_ the baseball idiot with us?” Gokudera wished he could fire laser-beams with his eyes.

“Gokudera-kun, Kawahira said to.”

“Ma, ma, Gokudera, calm down-”

“Why are we following that bastard's instructions?” Gokudera asked, frustrated and crinkling the map at the edges. Kawahira's hand-drawn directions were utterly useless.

“To find out our lineage,” Tsuna said feebly. That reason was sounding weaker and weaker the further they were from Japan.

They stood in the middle of the airport, not knowing which exit to take. 'Meet a friend here', the map told them, with a bunch of squiggly lines giving some feeble indication. But, as Gokudera pointed out, they had no idea who this friend was or even which way to hold the map. Customs was hell, mainly because Tsuna was permanently paranoid he would set off an alarm, and Yamamoto seemed to think laughing at bomb and weapons check was the appropriate behaviour.

Gokudera asked passer-bys for directions, and slowly the trio navigated to the nearest exit. And once they were outside, Gokudera relaxed slightly.

“That wasn't so bad, Juudaime,” Gokudera said optimistically.

“I suppose not,” Tsuna said nervously.

“That was fun,” Yamamoto said brightly.

“No one asked you,” Gokudera said irritably.

“Excuse me,” someone said in English from behind, “Are you-” he checked the paper, “-Gokudera, Yams, and Tuna?”

Gokudera hissed. “That's Sawada-sama to you.”

The boy blinked. “Uh, okay then? Sawada-sama.” He said it heavily accented. “The paper only says those names though.”

Gokudera scowled and snatched the sheet off of who they assumed was the 'friend'. “Damn Kawahira,” Gokudera muttered. “I'm going to kill him. Tuna? Juudaime as _tuna_?” He continued muttering curses, and Tsuna could've sworn he heard an _onmyou_ incantation in there.

“I'm Yamamoto, not 'yams,” Yamamoto said brightly. “And you are?”

Tsuna froze in place, not understanding anything anyone said. Even Yamamoto was speaking English.

“Will Solace,” he said, smiling back at Yamamoto easily. “Welcome to America. So, shall we get going?”

“Sure,” Yamamoto said, and Gokudera stuck out his tongue.

“So many sparkles,” the Storm grumbled.

“They certainly make a pair,” Tsuna agreed.

* * *

They hopped in a taxi (“Just like in the movies,” Yamamoto commented), made their way across New York (“Do you think we'll see a UMA?”) and wound up in the middle of a stretch of road. Tsuna swore he could waves, and could smell salt.

“Nearly there,” Will said, already marching off. Yamamoto jogged forwards, falling into pace with him and chatting easily.

Gokudera fell back with Tsuna, realising he was feeling lonely; Tsuna's lack of English was isolating him. “Juudaime, don't you think there's something weird about Solace?”

“What do you mean?” Tsuna asked curiously.

“He reminds me of mafioso,” Gokudera said, trailing off. “Oh well. It's probably nothing.”

“Yeah,” Tsuna said nervously. “Nothing.” But if Gokudera thought that...

“Here we are,” Will said, pointing at a massive pine tree. A golden fleece glimmered there, and a dragon-

“Oh my god, a UMA,” Gokudera whispered, before shrieking and running towards it.

“Uh, Gokudera, I wouldn't-” Will's panic was lost on Gokudera as he darted forwards. He cursed in some foreign language, before sprinting to try and catch up to Gokudera.

“He'll eat you,” Will shouted. “Go-” Will stumbled, and Tsuna was surprised; Will had, up until now, seemed to be the kind of guy who _never_ lost his balance. Yamamoto was also shouting, but the excited Gokudera didn't hear.

Tsuna panicked, practically shrieking, “Gokudera-kun, stop, please!”

Gokudera halted, nearly tripped. “J-Juudaime?” His face was painted with shame. “Oh...Juudaime, forgive me-” and he bowed so fast he nearly rolled down the hill again.

Tsuna, out of breath and now followed by Will and Yamamoto, waved him back up. “It's fine,” he panted. “Just- don't- run towards large dragons, okay?”

“Drakon,” Gokudera corrected. “Right?” He switched to English for Will.

Will was confused. “Huh?”

“A drakon, not a dragon,” Gokudera clarified.

“Yeah,” Will said, surprised. “How did you-”

“In my research about UMAs,” Gokudera said airily.

“You really do know everything,” Yamamoto commented.

“Of course.”

They continued up the hill, now giving the large snake a wide berth. One eye was open and studying the four. Tsuna's stomach was a riot of nerves by the time they reached the summit.

“Wow,” Yamamoto was the first to articulate as the three took in the sight of a sprawling camp. Numerous houses, with more being built, and a great hall, and a picnic area...Tsuna wondered if this was a holiday camp. (But it wasn't summer for them; Technically they were skipping school, something Hibari would bite them to death over.)

Yamamoto and Gokudera kept walking past the pine tree, followed by Will. But Tsuna stopped, feeling as though he would vomit.

Gokudera turned. “Juudaime?”

Tsuna shook his head. “I have a bad feeling.” He still wasn't past the tree.

“Juudaime,” Gokudera said again, Yamamoto also waiting expectantly.

“It'll be fine,” Will said, his voice soothing. Tsuna didn't understand, but he knew that tone.

“I can't,” Tsuna said.

“Yeah, you can,” Yamamoto said, baffled.

“I can't,” he said again. “My intuition...it says I can't.”

Gokudera looked appalled. “You can't walk past the tree?”

Tsuna had to try. Legs shaking, hands trembling, and heart in throat, he reached out a hand.

* * *

“I want you to keep the secret safe,” Timoteo said finally. A long winded explanation, Reborn thought tiredly. For something that could have been explained in a third of the time.

Reborn arched an eyebrow. “Why me? I'm already invested in Tsuna. I'm his _tutor._ ”

Timoteo studied him. When had the Ninth's eyes become so cold? “That's why. Tsuna trusts you. He'll listen, and you'll lead him down the wrong route.”

Reborn leaned back in his chair. “What's in it for me?”

Timoteo smiled – no, he _smirked._ “You'll get your adult body back.”

Reborn's heart nearly stopped. “My...adult body? How?”

“Verde,” was the answer. _Of course._ The mad scientist had been given access to all of Vongola's funding and technology. _Of course_ he had figured out a way.

“Now? Will I become an adult now?”

“It's guaranteed.” Timoteo knew he had Reborn. As much as Reborn hated it, he was going to accept this order.

“Under one condition.”

Timoteo's expression didn't waver. “Yes?”

“You give me my body back now. Before I complete the mission.” Reborn was firm on this.

“How do I know you won't turn against me?”

“I'm Reborn,” was the response. “I'm a lot of things, but I don't go back on a mission once I've accepted.”

“All very true,” Timoteo said, and Reborn wanted to smack the smug look off his face. The man was a snake. “I agree.”

* * *

Reborn fixed his suit in the mirror, studying his reflection. He admired his adult self, liked the face that looked back at him with confidence. “Sorry, Dame-Tsuna,” Reborn said, not really all that sorry. “Looks like I'm going to work against you this time around.”

 

**Notes for the Chapter:**

> if y'all are reading this w/o knowledge of both fandoms you gotta be so confused lmao


	2. UMAs Are Everywhere (Much To Gokudera's Delight)

**Notes for the Chapter:**

> too lazy...to proofread....lmao rip

Tsuna reached towards the barrier. He was terrified, his intuition going berserk. And for good reason.

He met resistance. He pressed against the invisible barrier, sickened to the core. He couldn't get through it. Another hand on the barrier, pleading with _whatever_ to let him in, and this time Gokudera was running to him.

“Juudaime,” Gokudera said, grabbing a wrist and tugging. While Gokudera's hand made it through, Tsuna was refused entry.

“What is this?” He muttered, wheeling around and pointing accusingly at Will. “What the fuck is this?”

Yamamoto's baseball bat was out. He was eyeing Will like his head was a ball he needed to hit to get a home run. “We're friends, right?” He asked, smile still in place.

Will looked at Yamamoto, flinching at the steel in his eyes. “I-I don't know why he's not going through...I assumed you were all demigods.”

“Ma, ma,” Yamamoto said, gesturing at the crowd that was gathering and Gokudera ignited his Flames, hoping to burn through the barrier. “Find a solution. We came here for a reason, and you're not stopping us.”

“That's not needed,” Tsuna said, raising his voice. “You two are taking this too seriously, I mean – I'm sure there's an answer?”

Will hesitated. “Yeah,” he said reluctantly. “But, uh-”

“Do it,” Yamamoto said, smile dropping.

“Yamamoto,” Tsuna complained, then glaring at Gokudera. “Gokudera-kun.” The Storm was still trying to burn a single spot of the barrier, using his body to block the campers' view.

Will licked his lips, also becoming acutely aware of the murmurs.

“Will?” Someone asked. “What's happening? The newbies giving trouble?”

“I, Will Solace, give Tsuna permission to enter Camp Half-Blood.” Will shifted on the spot, uneasy.

Tsuna fell in, Gokudera barely catching him. “Juudaime!”

“Will, you let a few runts order you around?” A buff girl in armour looked incredulous. “What the _hell-_ ”

Will brushed past her. “You don't sense it?”

Yamamoto had put away his baseball bat, smiling easily again, Gokudera also lightening up. Tsuna still looked sick, this time more from dread than anything else.

“Sense-?” The girl paused, narrowing her eyes at them. “...Oh.”

“Yeah, Clarisse,” Will said with a sigh. “These new campers? Trouble. If I didn't let Tsuna in...” he gave her a look. “A lot of us would've ended up wounded, or worse.”

The girl studied them. “I'll stick with you,” she decided. “Just to be sure.”

Will managed a wry smile. “Yeah, thanks.” He wouldn't be surprised if they were sons of Ares, with auras like those.

“Juudaime, are you hurt?”

“I'm fine,” Tsuna said, hoping Gokudera wouldn't decide to pick a fight with the whole camp.

“Are you sure?” Yamamoto also looked ready to kill.

“I'm sure.” Tsuna tried to sound firm and not at all bothered by a magical barrier that stopped him from entering. Oh no, magical barriers like that happened everyday.

“Juudai-” Gokudera cut off, distracted. “Um. A UMA?”

“Centaur,” said the centaur, and Tsuna shrieked.

“Where did he come from?” Tsuna gasped, barely catching his breath.

The man – no, centaur, Tsuna corrected – studied him amusedly. “And you're not the child of a god.”

Tsuna winced, then paused. “Uh, what?”

“What is the UMA talking about?”

“Gokudera, you shouldn't call him a UMA-”

“Shut it, baseball idiot, you-”

And a flash of light burst into life above Yamamoto. Tsuna shrieked again, twisting to see a glowing emblem of what Tsuna thought was a staff shining.

“A caduceus,” the centaur said. “A son of Hermes.”

“Hermes...” Gokudera trailed off. “Okay, Juudaime, forgive my language but: what the actual _fuck_ is happening?”

“My question exactly,” Tsuna muttered.

“It'll be fine,” Yamamoto brushed off.

“You're too accepting of this, idiot,” Gokudera snapped.

“Dear me, more troublemakers,” the centaur sighed, turning away.

* * *

They were seated at a picnic table, Tsuna, Yamamoto and Gokudera on one side, Chiron standing at the other. Tsuna was squished between his Guardians. (He was grateful he was so skinny.)

“Greek mythology.” Gokudera was wearing glasses with his hair tied back, leaning forward intently. “So, when you say the baseball idiot is a son of Hermes, you mean the actual god of messengers and thieves?” His sigh was explosive. “So UMAs are real.”

The centaur – Chiron – frowned. “UMA?”

“And Chiron, the one who trained Heracles?” Gokudera nodded. “So you really are immortal.”

“For as long as I'm needed,” Chiron said, eyeing Gokudera with curiosity. “You know a lot.”

Gokudera pushed his glasses up, puffing up. “I've studied this before.” He glanced at Tsuna eagerly.

“At least one of us knows what's happening,” Tsuna said hesitantly. “But uh. You know why I wasn't let in?”

Chiron looked at him sadly. Yamamoto and Gokudera tensed beside Tsuna as though expecting a fight.

“You're not a child of the gods,” Chiron said. “You're descended from another part of the Ancient Greek world.”

“Is that bad?”

“No,” Chiron said after a pause. “I know of monsters who are good.”

“Monsters,” Tsuna repeated faintly as Gokudera surged up, startling everyone who saw. “You callin' Juudaime a monster?” Gokudera had dynamite out, ready to throw it.

“Gokudera, calm down,” Yamamoto said, although he didn't look much calmer. “I'm sure it was just a poor choice of words. Right?” Yamamoto looked at Chiron with a smile.

The centaur nodded. “A poor choice, indeed.”

Gokudera sat down with a grumble. All three of them noted the tension in the armoured girl's posture as she watched them talk from a distance, Will also eyeing them with distrust.

“How about you three tell me about yourselves?”

The three traded looks. “Like what?” Tsuna asked.

“Your background, for starters. You're clearly not ordinary.”

“Juudaime?” Gokudera asked Tsuna. Both of them would take their cues from Tsuna – but how much should the young Decimo tell the camp?

“What's the name of this camp?”

“Camp Half-Blood,” was Chiron's answer. Tsuna looked at them both, seeking recognition. Gokudera shrugged and Yamamoto only smiled absently, meaning neither knew anything about this place.

Well, they were bound to find out anyway.

“We're mafia,” Tsuna told Chiron solemnly. The armoured girl and Will had edged closer, within earshot.

“Mafia,” Chiron repeated slowly. “And that's why Gokudera calls you, what was it, 'Juudaime'?”

“Yeah,” Tsuna said, anxiety building in his gut. “I'm the tenth Vongola boss, and these two are, well, subordinates?” He didn't know if he should explain the concept of _Guardians_ to him. He decided against it, just in case.

“I'm his right hand man,” Gokudera said, puffing up again.

“I might be, though,” Yamamoto said easily, causing Gokudera to glare at him.

“Baseball idiot-”

“And what brings you to America? Someone sent you, correct? We received a note in the fire to bring you here.”

“Well,” Tsuna said, a vague sense of panic building, “A man named Kawahira told us to come here in order to discover our lineage.”

Chiron raised an eyebrow. “Is that so? You trusted him enough to come here.”

“We've had run-ins with him before?”

“More than just run-ins,” Yamamoto commented. “We did have a big fight because of him.”

“A big fight-?”

All three fell silent. “It's over now, anyway,” Tsuna said, brushing it off.

* * *

They were taken to the Hermes cabin. Yamamoto laughed about how it reminded him of baseball, although Tsuna was sure any place he had visited because of baseball would have had less people crammed in such a small space.

“Unclaimed?” Someone asked loudly, the cabin falling silent as they scrutinised the three.

“This one is claimed,” Will said, pointing at Yamamoto. “The other two aren't.”

A loud groan. Tsuna flinched at it, Gokudera glaring at all of them before smiling at Tsuna. “Don't worry, Juudaime. Whoever's your parent will have to claim you. They can't just let the boss of Vongola go unclaimed.”

Will glanced at them strangely. “Vongola?”

Gokudera turned his glare to Will. “Vongola.”

“Gokudera-kun, don't start any fights.” Tsuna sounded _done._

Gokudera nodded. “Yeah, Juudaime. I'll try not to.”

_Famous last words,_ Tsuna couldn't help but think.

**Notes for the Chapter:**

> crappy chapter? yeah. s'gonna be an entire fic like that *winks w/ both eyes*


	3. Looking for a Fight™

**Notes for the Chapter:**

> //throws a wild update then sinks back into the void//

There were at the campfire when Gokudera was claimed.

They didn't know the songs, and Tsuna certainly didn't understand _anything_ anyone was saying at him. He only watched the changing flames in the centre, admiring how bright it was.

And naturally, Gokudera being Gokudera, a fight broke out.

Something about Gokudera smoking, Tsuna knew, given Gokudera had petulantly lit up several more and let the smoke disperse. Said person fighting him grabbed a few and stamped on them, jabbing at Gokudera.

“Gokudera-kun,” Tsuna began, alarmed when it looked like the dynamite would be coming out. Gokudera spat something in English, Yamamoto grabbing his arm to tug him back to his seat.

“Baseball idiot, let go,” Gokudera snapped, the only words Tsuna understood in the whole exchange.

All eyes were on them, although Tsuna found it odd that no one intervened. Of course, no one stopped the fight because the black and orange symbol blazing above Gokudera's head.

A complicated symbol, was Tsuna's first thought. He squinted at it, then glanced at everyone else to see if they knew what it was.

“Hecate,” Someone said.

_Hecate?_ Tsuna assumed that was the name of whoever owned that symbol. “Gokudera-kun,” he said, pointing.

Gokudera stopped for long enough to obey the direction where Tsuna pointed. He saw the symbol, now fading from view.

“Hecate,” he said, surprised. Then something dark crossed his face. “The goddess of magic,” he explained to Tsuna, still looking troubled.

“M-Magic, you say,” Tsuna said, voice uncomfortably high. “Like, _magic_ magic?”

“Juudaime...” Gokudera looked at him, concerned. “Calm down.”

Calm down, Tsuna thought. Like dealing with a whole other world wasn't worth panicking over.

* * *

Gokudera couldn't sleep, and ended up crawling out of his (new) bed at around 3am to sit by the lake. He stared out at the calm water, ignoring the faces of the women-

_Wait, women?_ Gokudera shook his head furiously, plopping back down and sighing. Of course there weren't beautiful women in the lake, he told himself tiredly, disregarding everything he'd learned about Greek myth in favour of his own peace of mind. If naiads were real, he'd have found them ages ago (during his nymph-cryptid-hunting phase).

"Hecate, huh." Gokudera lit a cigarette, knuckles itching to punch Kawahira in the face. Damn that alien for sending them here. Gokudera's mother was Lavina, not some goddess who never bothered to show up once in his life.

"Ah, Gokudera," Yamamoto said, approaching from behind, startling Gokudera. He hadn't heard his footsteps, but judging by the flatness in Yamamoto's eyes, he'd been in full hitman-mode anyway.

"Baseball idiot," Gokudera said, more out of habit than anything. He was now smoking three cigarettes.

He thought the forest across the lake was giving him dirty looks. But trees don't do that, Gokudera once again told himself. Dryads weren't real, just like naiads were all fictional as well.

(Even if there were shapes of women in the trees and the lake, all looking at him.)

"Came here to think as well, huh." Yamamoto sat beside Gokudera.

“Not so close,” Gokudera snapped. Yamamoto laughed and moved away from Gokudera.

“Hermes sure has had a lot of kids, huh.”

“God of travellers,” Gokudera reminded him, annoyed.

“Right, right.” A cloud passed over Yamamoto's face before it cleared up.

(Or maybe he was hiding his pain, Gokudera wondered.)

“This is a good spot,” Yamamoto sighed, leaning back. “I came out here to try and centre myself. I didn't want to worry Tsuna, after all.”

"I didn't want to worry Juudaime either, so I thought I'd clear my head before seeing him this morning." Gokudera was surprised at how much he was saying, but he supposed he needed to get the words out.

"I had a similar thought," Yamamoto said. “Do you know anything about the claiming?”

“No. It sounds like a modern thing, I think. The claiming – I'll ask around.” Ask around, as in intimidate some campers into coughing up.

“Maybe it's like a descent thing, like how Tsuna's inheriting Vongola,” Yamamoto said hopefully.

_Hermes_ , Gokudera pondered. "What does that make your old man? Hermes's grandchild, or something?”

"Maybe it's like, he's my uncle." Yamamoto grinned.

"That doesn't make sense," Gokudera hissed.

Yamamoto shrugged. "Who knows. This whole claiming thing's weird."

_Mother,_ Gokudera thought, biting on his thumb. Was Lavina really not his mother?

"Dammit," Gokudera spat after a while, punching the ground. "I want to know for certain.”

"We'll have to ask, huh."

"Dammit," Gokudera said again, “dammit, _dammit,_ why the fuck did we have to come here?”

To find out their lives were lies? Yamamoto and Gokudera were in the same boat – something Gokudera only reluctantly admitted. Both of them were losing their blood connections to the parent they actually gave a shit about.

Not to mention Tsuna's own bloodline was being called into question. Not a child of the gods – but like hell that was going to sway Gokudera's loyalty.

Both of them were so caught up in their thoughts that before they knew, the sun was rising and the camp was coming back to life.

* * *

That morning, Tsuna found Yamamoto and Gokudera brooding besides the lake before breakfast. They were sitting on the grass a few feet away from each other.

"Juudaime," Gokudera said, perking up when he saw Tsuna approaching.

"Tsuna," Yamamoto greeted, nodding at him.

"Shouldn't we be going to get breakfast?" Tsuna blurted out nervously.

Gokudera stood. "I'll go with you, then."

"I think I'll stay here a bit longer," Yamamoto said sheepishly. "You guys go ahead."

"Like I'd wait for you," Gokudera grumbled, but Tsuna thought it sounded half-hearted.

"What were you talking about?" Tsuna asked.

"Nothing, Juudaime," Gokudera said, a little too hastily for Tsuna's liking. Not wanting to push them, Tsuna let the subject drop. In any case, his stomach was crying out for food.

 

**Notes for the Chapter:**

> yeah, I know that harpies should be out and about hunting down naughty campers who are hanging out after lights-out (p sure that's in the books, anyway, lol). that'll be explained next chapter, if I remember to.
> 
> also theRE'S NO JOKING AROUND IN THIS WTF @ ME. WHO AM I. just an entire chapter of dera's angst lol
> 
> the next chapter will probs have a timeskip or smth, bc I wanna start the main storyline kek


End file.
